This section provides background information related to the present disclosure which is not necessarily prior art.
Capacity modulation is often a desirable feature to incorporate into the compressors of refrigeration, heat pump, HVAC, or chiller system (generically, “climate control systems”) systems in order to better accommodate the wide range of loading to which the systems may be subjected. Many different approaches have been utilized for providing this capacity modulation feature. These approaches have ranged from control of the suction inlet of the compressor to bypassing compressed discharge gas back into the suction pressure zone of the compressor. With a scroll-type compressor, capacity modulation has often been accomplished by using a delayed suction approach which comprises providing ports at various positions along the scroll wrap which, when opened, allow the initially formed compression chambers between the intermeshing scroll wraps to communicate with the suction zone of the compressor, thereby delaying the point at which the sealed compression chambers are formed and, thus, delaying the start of compression of the suction gas. Such a method of capacity modulation can have the effect of reducing the compression ratio of the compressor. While these delayed suction systems are effective at reducing the capacity of the compressor, they are only able to provide a predetermined amount of compressor unloading with the amount being determined by the position of the unloading ports along the scroll wraps.